It is conventional practice in the raising of cattle in the United States and in certain other countries, to confine them in so-called feedlots or feedyards where they are fed high-value feed mixes enriched with proteins, carbohydrates, fats, vitamins and minerals to achieve a relatively rapid gain in weight.
The animal industry generally in the United States produces about 2 billion tons of animal manure a year. For example, such feedlots or feedyards may often contain as many as 2,000 to 50,000 head of cattle in a relatively small area. Typically, an average of 18 pounds (dry weight) per day of high value feed mixes must be fed to each animal for maintenance and to produce a daily average increase in weight of 11/2 to 23/4 pounds. This average animal voids approximately 6 pounds of dry weight per 24 hour period. Typically the manure is merely removed periodically from the confined areas and stockpiled, pressed into blocks and in some cases a small amount has been used on fields as humus. Animal wastes are thus accumulated in localized areas and become sources of air and water pollution. The amount of animal waste generated in the United States is about 10 times that of human waste and 70% of this animal waste is from cattle.
The treatment of animal waste has always received attention but this attention has increased lately because of environmental considerations. Attempts have been made to recover nutrients from manure, see U.S. Pat. Nos. 4,117,175 and 4,018,650. U.S. Pat. No. 3,546,812 teaches treating similar wastes by the addition of microorganisms. U.S. Pat. No. 4,134,749 is also of interest in this area.
Ruminants possess the unique ability to utilize nonprotein nitrogen sources to fulfill a major portion of their dietary protein requirements. These include urea and ammonium salts of organic acids such as ammonium lactate, ammonium acetate and ammonium propionate. It has been proven that ammonium salts are equivalent to soybean meal and superior to urea as a nitrogen supplement when fed to feedlot cattle. See "Fermentative Conversion of Potato Processing Wastes into a Crude Protein Feed Supplement by Lactobacilli", Forney, L. J. et al., Vol. 18, Developments in Industrial Microbiology, proceedings of the 33rd general meeting of the Society for Industrial Microbiology, Aug. 14-20, 1976, Jekyl Island, Ga., Pages 135-143.
Thus, there exists the need to treat animal waste either as a soil extender without any environmental concerns or with modification as a feed for cattle.